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css · whitespace · comments · live

Minify CSS to one compact line

Strip comments, normalise whitespace, and remove redundant semicolons. A single-line minifier you can run from any browser tab. Runs locally.

CSS Minifier
Input
101 B
7 lines
Output
67 B
1 lines
Status
ready
live
Ratio
0.66×
out/in
input · css
output · minified css
.card{padding:8px;color:red;background:#fff}.card:hover{color:blue}
Quick Start

How to minify CSS

Strips comments, collapses runs of whitespace, and trims separators around : ; , so the rules compact onto one line.

  1. 01

    Paste CSS

    Authored stylesheets, devtools copies, or a small design system.

    Parsing runs through Prettier’s standalone bundle (or the language-specific equivalent) loaded lazily — no parser ships until the tool is opened.

    cssPrettierASTstandalonelazy
    input · sourceraw · AST
    .a { color: red; }
    loaded · parsedAST · ready
  2. 02

    Comments removed

    /* ... */ blocks are stripped completely — they never made it to the browser anyway.

    Indent width, tab style, and print-width re-format through a memoised pass — switching 2 → 4 spaces never re-parses, only re-prints.

    stripindentprint-widthmemoisedlive
    step · optionscomments · live
    /* note */ → ""
    options applied · livelive
  3. 03

    Whitespace squashed

    Multiple spaces and newlines collapse; separators get tight.

    The formatter is deterministic and idempotent: running it twice produces byte-identical output, which keeps diffs and git noise to a minimum.

    compactidempotentdeterministicdiff-cleanstable
    step · formattedwhitespace · ready
    .a{color:red}
    formatted · liveidempotent
  4. 04

    Copy or download

    One-line .css ready to drop into a build artefact.

    Download writes a Blob with the language-appropriate extension; copy uses navigator.clipboard.writeText so the output preserves all whitespace exactly.

    exportclipboardbloblanguage MIMEclient-side
    ok · copiedready · done
    ✓ Copied
    shipped · ready to shipsuccess
Pro tips

Formatting tips that keep diffs sane

Pick one config and pin it

Inconsistent formatting causes diff churn. Commit .prettierrc / .editorconfig and enforce in CI.

Format on save

Editor integration is faster feedback than a pre-commit hook. Use both for belt-and-braces.

Idempotency matters

Running the formatter twice should produce identical output. Test this on a representative file.

Match the language community

Default to community conventions: 2 spaces for JS/CSS, 4 for Python, tabs for Go. Fights over indent are a productivity tax.

Print-width drives wrapping

80, 100, and 120 are the common targets. Wider lines parse fast but review slower side-by-side.

Don’t mix formatters and linters

Prettier handles whitespace; ESLint handles correctness. Disable overlapping rules to avoid fight-club configs.

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Use Cases

When to minify CSS

Inline critical CSS, embedded HTML, build comparison.

Critical CSS

Inline minified CSS in <head> for above-the-fold rendering. Idempotent: running the formatter twice produces byte-identical output, which is the foundation of a clean CI gate. Pair with a pre-commit hook so PRs arrive already formatted, focusing review on logic.

idempotent

Embedded HTML

Drop CSS into email templates or sandboxed iframes. Pairs with EditorConfig + .prettierrc for end-to-end consistency. Whitespace-only changes vanish so reviewers see real diffs, and git blame stays honest about who wrote what.

CI-ready

Build comparison

Compare your bundler's output against this baseline. Output respects your indent width, tab style, and print-width — settings carry over for repeat runs. Switching 2-space to 4-space costs nothing in CPU but standardises an entire codebase.

diff-clean

Size budget

Quickly estimate the cost of a stylesheet change. Format-on-save is the fastest feedback loop; CI is the safety net. Together they make inconsistent indentation a thing of the past and free up review cycles for genuine concerns.

PR-friendly

Quick share

Paste a compact one-liner into chat or a gist. Whitespace-only changes don't trigger downstream content-hash invalidations, so CDN cache keys and CI cache layers stay warm. Real changes get all the rebuild budget.

review-ready

Static site embed

Bake CSS into a static HTML page with no build step. Pairs with linters (ESLint, Stylelint, pylint) that catch what formatting alone can't — bugs, unused imports, dead code. Each tool stays in its lane, and the codebase stays clean.

deterministic
FAQ

Frequently asked questions

No. Only whitespace, comments, and redundant separators are touched.
Yes — properties are kept verbatim including -webkit / -moz prefixes.
Custom properties (--var) are preserved exactly; whitespace inside values is collapsed.
Yes — @media and other at-rules are kept intact.
No — the minifier runs locally in your browser tab.
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